Aerodynamically efficient lightweight vertical take-off and landing aircraft with pivoting rotors and stowing rotor blades

ABSTRACT

An aerial vehicle adapted for vertical takeoff and landing using a set of wing mounted thrust producing elements and a set of tail mounted rotors for takeoff and landing. An aerial vehicle which is adapted to vertical takeoff with the rotors in a rotated, take-off attitude then transitions to a horizontal flight path, with the rotors rotated to a typical horizontal configuration. The aerial vehicle uses different configurations of its wing mounted rotors and propellers to reduce drag in all flight modes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/218,845 to Bevirt et al., filed Mar. 18, 2014, which is herebyincorporated by reference in its entirety.

BACKGROUND

Field of the Invention

This invention relates to powered flight, and more specifically to avertical take-off and landing aircraft with pivoting rotors and stowingrotor blades.

Description of Related Art

There are generally three types of vertical takeoff and landing (VTOL)configurations: wing type configurations having a fuselage withrotatable wings and engines or fixed wings with vectored thrust enginesfor vertical and horizontal translational flight; helicopter typeconfiguration having a fuselage with a rotor mounted above whichprovides lift and thrust; and ducted type configurations having afuselage with a ducted rotor system which provides translational flightas well as vertical takeoff and landing capabilities.

The amount of thrust required to take-off in a vertical take-offscenario greatly exceeds the thrust needed to keep the same vehiclealoft during forward flight, when the wings are providing lift. Theamount of thrust required to transition from a vertical take-off mode tohorizontal, forward, flight mode may also be quite high. Thus, there maybe a mismatch between the power requirements if there are notpossibilities to change power delivery paradigms during flight.

In order to provide efficiency in both vertical take-off and forwardflight modes, improvements to past systems must be made. What is calledfor is a vertical take-off and landing aircraft that incorporatesefficiencies into all use modes.

SUMMARY

An aerial vehicle adapted for vertical takeoff and landing using a setof wing mounted thrust producing elements and a set of tail mountedrotors for takeoff and landing. An aerial vehicle which is adapted tovertical takeoff with the rotors in a rotated, take-off attitude thentransitions to a horizontal flight path, with the rotors rotated to atypical horizontal configuration. The aerial vehicle uses differentconfigurations of its wing mounted rotors and propellers to reduce dragin all flight modes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an aerial vehicle in forward flightaccording to a first embodiment of the present invention.

FIG. 2 is a side view of an aerial vehicle in a forward flightconfiguration according to a first embodiment of the present invention.

FIG. 3 is a top view of an aerial vehicle in a forward flightconfiguration according to a first embodiment of the present invention.

FIG. 4 is a front view of an aerial vehicle in a forward flightconfiguration according to a first embodiment of the present invention.

FIG. 5 is a perspective view of an aerial vehicle in takeoffconfiguration according to a first embodiment of the present invention.

FIG. 6 is a front view of an aerial vehicle in takeoff configurationaccording to a first embodiment of the present invention.

FIG. 7 is a side view of an aerial vehicle in takeoff configurationaccording to a first embodiment of the present invention.

FIG. 8 is a perspective view of an aerial vehicle in a transitionconfiguration according to a first embodiment of the present invention.

FIG. 9 is a sequence of views illustrating transition of the wingaccording to a first embodiment of the present invention.

FIG. 10 is a perspective view of an aerial vehicle in forward flightwith wing rotor blades stowed according to a first embodiment of thepresent invention.

FIG. 11 is a front view of an aerial vehicle in a forward flightconfiguration with wing rotor blades stowed according to a firstembodiment of the present invention.

FIG. 12 is a top view of an aerial vehicle in a forward flightconfiguration with wing rotor blades stowed according to a firstembodiment of the present invention.

FIG. 13 is a side view of an aerial vehicle in a forward flightconfiguration with wing rotor blades stowed according to a firstembodiment of the present invention.

FIG. 14 is a perspective view of a wing rotor with the front coverremoved for clarity according to some embodiments of the presentinvention.

FIG. 15 is a front view of a wing rotor with the front cover removed forclarity according to some embodiments of the present invention.

FIG. 16 is a side view of a wing rotor with its blades deployedaccording to some embodiments of the present invention.

FIG. 17 is a side view of a wing rotor with its blades stowing accordingto some embodiments of the present invention.

FIG. 18 is a side view of a wing rotor with its blades stowing accordingto some embodiments of the present invention.

FIG. 19 is a side view of a wing rotor with its blades stowing accordingto some embodiments of the present invention.

FIG. 20 is a side view of a wing rotor with its blades stowed accordingto some embodiments of the present invention.

FIG. 21 is a perspective view of a tail rotor according to someembodiments of the present invention.

FIG. 22 is a side view of a tail rotor in a forward flight configurationaccording to some embodiments of the present invention.

FIG. 23 is a side view of a tail rotor in a take-off configuration tosome embodiments of the present invention.

FIG. 24 is a side view of a tail rotor and its deployment mechanism in astowed configuration according to some embodiments of the presentinvention.

FIG. 25 is a side view of a tail rotor and its deployment mechanismmoving from a stowed configuration according to some embodiments of thepresent invention.

FIG. 26 is a side view of a tail rotor and its deployment mechanismmoving from a stowed configuration according to some embodiments of thepresent invention.

FIG. 27 is a side view of a tail rotor and its deployment mechanism in adeployed configuration according to some embodiments of the presentinvention.

FIG. 28 is a front view of a tail rotor and its deployment mechanism ina deployed configuration according to some embodiments of the presentinvention.

FIG. 29 is a perspective view of an aerial vehicle in take-offconfiguration according to a second embodiment of the present invention.

FIG. 30 is a front view of an aerial vehicle in take-off configurationaccording to a second embodiment of the present invention.

FIG. 31 is a side view of an aerial vehicle in take-off configurationaccording to a second embodiment of the present invention.

FIG. 32 is a top view of an aerial vehicle in take-off configurationaccording to a second embodiment of the present invention.

FIG. 33 is a perspective view of an aerial vehicle in a forward flightconfiguration according to a second embodiment of the present invention.

FIG. 34 is a front view of an aerial vehicle in a forward flightconfiguration according to a second embodiment of the present invention.

FIG. 35 is a side view of an aerial vehicle in a forward flightconfiguration according to a second embodiment of the present invention.

FIG. 36 is a top view of an aerial vehicle in a forward configurationaccording to a second embodiment of the present invention.

FIG. 37 is a side view illustrating nested blades according to someembodiments of the present invention.

FIG. 38 is a side view of a deployed rotor unit with rotor bladesextended according to some embodiments of the present invention.

FIG. 39 is a side view of rotor unit with two blade sets in a forwardflight mode according to some embodiments of the present invention.

FIG. 40 is a side view of rotor unit with two blade sets in a take-offmode according to some embodiments of the present invention.

FIG. 41 is a front view of an electric motor according to someembodiments of the present invention.

FIG. 42 is a partial view of a directional clutch in an electric motoraccording to some embodiments of the present invention.

FIG. 43 is a partial view of a directional clutch in an electric motoraccording to some embodiments of the present invention.

FIG. 44 is a partial cross-sectional view of directional clutches in anelectric motor according to some embodiments of the present invention.

FIG. 45 is a perspective view of an aerial vehicle in take-offconfiguration according to a third embodiment of the present invention.

FIG. 46 is a front view of an aerial vehicle in take-off configurationaccording to a third embodiment of the present invention.

FIG. 47 is a top view of an aerial vehicle in take-off configurationaccording to a third embodiment of the present invention.

FIG. 48 is a side view of an aerial vehicle in take-off configurationaccording to a third embodiment of the present invention.

FIG. 49 is a perspective view of an aerial vehicle according to a fourthembodiment of the present invention.

FIG. 50 is a front view of an aerial vehicle in a take-off configurationaccording to a fourth embodiment of the present invention.

FIG. 51 is a top view of an aerial vehicle in a take-off configurationaccording to a fourth embodiment of the present invention.

FIG. 52 is a side view of an aerial vehicle in a take-off configurationaccording to a fourth embodiment of the present invention.

FIG. 53 is a perspective view of an aerial vehicle in a forward flightconfiguration according to a fourth embodiment of the present invention.

FIG. 54 is a top view of an aerial vehicle in a forward flightconfiguration according to a fourth embodiment of the present invention.

FIG. 55 is a front view of an aerial vehicle in a forward flightconfiguration according to a fourth embodiment of the present invention.

FIG. 56 is a side view of an aerial vehicle in a forward flightconfiguration according to a fourth embodiment of the present invention.

DETAILED DESCRIPTION

Although vertical takeoff and landing (VTOL) aircraft have always beendesired, compromises in the realization of these aircraft have limitedtheir usefulness and adoption to certain niches. The thrust needed forVTOL is significantly higher than the thrust needed to maintainhorizontal flight. The vertical take-off thrust may also be neededduring the transition to forward flight. Once moving in forward flight,the wings of the aircraft provide lift, supplanting a function deliveredby motors during VTOL and during transition. Thrust producing elementsneeded during take-off, but not during forward flight, may be alteredduring forward flight such that they impart less drag onto the flyingsystem.

In some aspects, an aerial vehicle may use bladed propellers powered byelectric motors to provide thrust during take-off. The propeller/motorunits may be referred to as rotor assemblies. In some aspects, the wingsof the aerial vehicle may rotate, with the leading edges facing upwards,such that the propellers provide vertical thrust for take-off andlanding. In some aspects, the motor driven propeller units on the wingsmay themselves rotate relative to a fixed wing, such that the propellersprovide vertical thrust for take-off and landing. The rotation of themotor driven propeller units may allow for directional change of thrustby rotating both the propeller and the electric motor, thus notrequiring any gimbaling, or other method, of torque drive around orthrough a rotating joint.

In some aspects, some or all of the wing mounted motor driven rotors areadapted to have the rotor blades fold back into a stowed positionwherein the blades nest in recesses in the adjoining nacelle body aftera transition to horizontal flight. The nested blades may result in asignificantly lower drag of the aerial vehicle, while also allowing asignificantly reduced power usage with only some of the rotors providingforward thrust.

In some aspects, extended nacelles with two coaxial propellers are usedsuch that one of the propellers is used during forward flight, andanother during vertical take-off and landing. The VTOL propeller may beadapted to nest its blades during forward flight. In some aspects, theextended nacelle may reside at the tip of a wing, or at the end of arear V-tail element, and be adapted to rotate such that the VTOLpropeller may provide vertical thrust during take-off and landing. Insome aspects, each of the coaxial propellers has its own electric motor.In some aspects, the coaxial propellers are driven by the same electricmotor. In some aspects, the electric motor has directional clutches suchthat one propeller is driven while the motor rotates in a firstdirection, and the other propeller is driven while the motor rotates ina second direction.

In some aspects, the motor driven rotors attached to the wing areadapted to place the mass of the motor and rotor significantly forwardof the wing. In some aspects, this forward location allows for therotation of the rotors to a vertical thrust orientation that has theairflow predominantly in front of the leading edge of the wing, reducingair flow impingement by the wing during VTOL operations. In someaspects, this forward location of the mass of the rotors and motorsallows for unusual wing configurations, such as swept forward wings,whose otherwise possible drawbacks during higher g-force maneuvers arepartially or fully moderated by this mass placement.

In some aspects, the mass balance of the aerial vehicle may be alteredby movement of masses such as the battery mass. In some aspects, thebattery mass may be adjusted to retain balance when a single vs. amulti-passenger load is supported. In some aspects, mass balance may beadjusted in automatic response to sensors within the aerial vehicle. Insome aspects, the battery mass may be distributed between a two or morebattery packs. The battery packs may be mounted such that their positionmay be changed during flight in response to changes in the balance ofthe aerial vehicle. In some aspects, the flight control system of theaerial vehicle may sense differential thrust requirements duringvertical take-off and landing, and may move the battery mass in order toachieve a more balanced thrust distribution across the rotor assemblies.In some aspects, the battery mass may be moved should there be a failureof a rotor assembly during transition or vertical take-off and landing,again to balance the thrust demands of the various remaining functioningrotors.

In a first embodiment of the present invention, as seen in FIGS. 1-4, anaerial vehicle 100 is seen in first forward flight configuration, aswould be seen just after having transitioned from a vertical take-offconfiguration. In another forward flight mode, the blades of the wingmounted rotors will stow and nest, as discussed below. The aircraft body101 supports a left wing 102 and a right wing 103. Motor driven rotorunits 106 include propellers 107 which may stow and nest into thenacelle body. The aircraft body 101 extends rearward is also attached toraised rear stabilizers 104. The rear stabilizers have rear motors 105attached thereto. In some aspects, the rear motors may also have fronthubs, or spinners, which are omitted from some Figures for illustrativepurposes.

As seen in top view in FIG. 3, the wings 102, 103 are partially sweptforward. Aerial vehicles according to embodiments of the presentinvention may include partially or wholly forward swept wings withspanwise distributed masses located forward of the leading edge. Thedivergent aeroelastic torsion commonly seen in forward-swept wingdesigns is substantially reduced by the presence of the massescantilevered forward of the wing, which create opposing torque. As seenin FIGS. 2 and 3, the wing rotor assemblies 106 are mounted forward ofthe wing leading edge, and are also then forward of the neutral axis ofthe wing.

FIGS. 5-7 illustrate the aerial vehicle 100 in a vertical take-off andlanding configuration such that the thrust of the rotors is directedupward. The wing 102, 103 have been rotated relative to the body 101around a pivot 108. In some embodiments, the wings are fixed to eachother with structure that crosses through the vehicle body 101. As seenin side view in FIG. 7, whereas the wing rotors 107 have had theirthrust redirected for vertical take-off due to the rotation of the wing,the rear rotors 105 have had their thrust redirected due to theirrotation relative to the rear stabilizers 104. Although referred toabove as a pivot, the attachment of the wing to the aerial vehicle bodymay use a linkage adapted to maintain a forward position of the mass ofthe wing and rotor assemblies.

FIGS. 21-28 illustrate the configurations of the rear rotor. Thedeployment of a rear rotor from a stowed, forward flight, configurationto a deployed, vertical take-off, position, as well as a variety ofintervening positions, may be achieved using a deployment mechanismwhich rotates the rotor relative to the rear stabilizers. FIG. 22illustrates a stowed, forward flight, configuration of rear rotor unit105. The rear nacelle portion 115 may be rigidly mounted to a rearstabilizer in some embodiments. The spinner 114 and the motor cover 113provide aerodynamic surfaces for the front portion of the nacelle. Thepropeller 111 extends through the spinner 114. In a fully deployedposition, as seen in FIG. 23, and in a partial front view in FIG. 28,the motor 110, motor cover 113, spinner 114, and propeller 111 haverotated to a position adapted to provide vertical thrust. The electricmotor/propeller combination being on the outboard side of thearticulating joint allows for a rigid mounting of the propeller to themotor, which is maintained even as the propeller is moved throughvarious attitudes relative to the rear nacelle portion. With such aconfiguration the rotating power from the motor need not be gimbaled orotherwise transferred across a rotating joint.

FIGS. 24-27 illustrate a sequence of positions of the motor andpropeller relative to the rear nacelle, also to the rear tail structureof the aerial vehicle. As the articulating portion of the rear rotorunit begins its deployment, it can be seen in FIG. 25 that the linkagesfirst deploy the articulating portion forward, as opposed to merelypivoting around a single pivot point. The multi-bar linkage allows forthe use of a single actuator for this complex deployment. FIG. 26illustrates the rear rotor unit as it does rise above the top of therear nacelle, and achieves full deployment as seen in FIG. 27. With themulti-bar linkage the motion of the articulating portion, which includesthe motor, propeller, and spinner, is almost horizontal at the positionof full deployment. As the thrust direction of the rotor is vertical inthe fully deployed position, the actuator powering the deployment of themulti-bar linkage is not required to offset, or counteract, the thrustof the rotor.

FIG. 9 illustrates various positions of the wing and rear rotors aswould be seen during transition from take-off to forward flight mode, orfrom forward flight mode to vertical take-off and landing mode. After avertical take-off, the rotors transition from a configuration providingvertical thrust through positions rotating towards the horizontal. Asthe forward speed of the aerial vehicle increases, the wings begin togenerate lift such that not as much vertical thrust is needed tomaintain altitude. With sufficient forward speed, lift is maintained bythe wings and the thrust needed for forward flight is able to beprovided by fewer rotors. In some aspects, the wings are raised to avertical take-off configuration with the use of a linkage adapted toslide the wing pivot forward as the wing reaches deployment. This allowsfor a more favorable compromise in center of gravity location betweenVTOL and forward flight modes by locating the wing-mounted rotorassemblies farther forward in the VTOL configuration.

FIGS. 10-13 illustrate a forward flight configuration of the aerialvehicle 100 according to some embodiment of the present invention. Thepropeller blades of the wing mounted rotors 106 have been stowed and arenested within recesses along the nacelle. As forward flight requiressignificantly less thrust than required for vertical take-off, many ofthe individual motors and rotors may be deactivated during forwardflight. To reduce drag, the blades may be folded back into a stowedposition. To further reduce drag, the nacelles may have recesses suchthat the folded blades are adapted to nest within the recesses, creatinga very low drag nacelle during forward flight. The rear rotors 105 maybe used to provide forward thrust during this forward flightconfiguration.

FIG. 14 illustrates a front set of views of a stowing blade set as itstows from a fully deployed configuration to a fully stowedconfiguration. The blades nest into recesses along the nacelle such thatthe stowed blade set gives the effective wetted area of a simplenacelle. FIG. 15 illustrates a wing mounted rotor unit according to someembodiments as it stows from a fully deployed configuration to a stowedconfiguration. Of note is that the rotor assembly, which may comprise anelectric motor, the blade set, and the spinner, may itself deploy as awhole as seen in FIG. 38, for example. In some aspects, the deploymentof the rotor assembly utilizes a linkage, such as the linkage 209 ofFIG. 38, which deploys the rotor to a vertical position whilesimultaneously pushing it forward and away from the remaining body ofthe nacelle. The push away from the remaining body of the nacellereduces the download in the wing from the downwash of the associatedrotor.

FIGS. 16-20 illustrate a sequence of positions as the blades 107 of awing mounted rotor 106 fold down into a stowed position. FIG. 16illustrates the propeller blades 107 fully deployed, as would be used invertical take-off and landing, and during transition to horizontal,forward, flight. Thus succeeding figures illustrate the blades 107folding down to a stowed position. As seen in FIG. 20, the blades 107fit within recesses 116 in the nacelle resulting in a low dragconfiguration 117.

In an exemplary configuration of the first embodiment, the aerialvehicle has 8 rotors and weighs 900 kg. The rotor diameters are 1.3meters, with a thrust per rotor of 1100 N. The continuous rpm of themotor at sea level is 1570 rpm, with a maximum of 1920 rpm. The wingspanis 8.5 meters. The battery mass is 320 kg, and the mass per motor is 20kg. The cruise speed is 320 km/h. The continuous hover shaft power permotor is 29 kW.

In a second embodiment of the present invention, as seen in a verticaltake-off configuration in FIGS. 29-32, an aerial vehicle 200 usesforward swept fixed wings 202, 203 with rotors of different typesadapted for both vertical take-off and landing and for forward flight.The aircraft body 201 supports a left wing 202 and a right wing 203.Motor driven rotor assemblies 206, 207 on the wings include propellerswhich may stow and nest into the nacelle body. The aircraft body 201extends rearward is also attached to raised rear stabilizers 204. Therear stabilizers have rear rotor assemblies 205, 208 attached thereto.The aerial vehicle 200 is seen with two passenger seats side by side, aswell as landing gear under the body 201. Although two passenger seatsare illustrated, other numbers of passengers may be accommodated indiffering embodiments of the present invention.

As seen in top view in FIG. 32, the wings 202, 203 are swept forward.Aerial vehicles according to embodiments of the present invention mayinclude partially or wholly forward swept wings with spanwisedistributed masses located forward of the leading edge. The divergentaeroelastic torsion commonly seen in forward-swept wing designs issubstantially reduced by the presence of the masses cantilevered forwardof the wing, which create opposing torque. Also seen in the top view ofFIG. 32 is that the propellers of the wing mounted motor driven rotorunits are extended forward with, and from, their nacelles such that theair flow in vertical take-off mode is not substantially interfered withby the wings. Similarly, the propellers of the rear stabilizer mountedmotor driven rotor units are extended forward with, and from, theirnacelles such that the air flow in vertical take-off mode is notsubstantially interfered with by the rear stabilizers. An illustrationof the linkage that may be used to extend the rotors in the verticalconfiguration may be seen in FIG. 38.

Another aspect of the forward swept wing configuration is that it allowsfor the wings 202, 203 to be mounted to the body 201 somewhat rearwardof where they may have attached otherwise. The rearward attachmentallows for a spar connecting the wings to traverse the interior of theaerial vehicle body to the rear of the passenger seats. A further aspectof the forward swept wing with articulating rotors in VTOL mode is theforward stagger of the vertical rotors, which improves longitudinalcontrol authority in vertical and transitional flight for a given wingroot location by lengthening the moment arm of these rotors about thecenter of gravity. This is especially helpful in the case of a failurein one of the rear mounted rotors during VTOL modes. Additionally, themore even longitudinal rotor distribution effected by this configurationreduces the highest torque of the motors required to maintain levelvertical flight in worst-case single motor or rotor failure eventuality,allowing the motor size to be reduced.

In some aspects, a portion of the wing mounted rotors may be adapted tobe used in a forward flight configuration, while other wing mountedrotors may be adapted to be fully stowed during regular, forward,flight. The aerial vehicle 200 may have four rotors on the right wing203 and four rotors on the left wing 202. Three of the rotor assemblieson each wing may have wing mounted rotors 206 that are adapted to flipup into a deployed position for vertical take-off and landing, to bemoved back towards a stowed position during transition to forwardflight, and then to have their blades stowed, and nested, during forwardflight. The fourth rotor assembly 207 may include a second set of bladesto be used for forward flight, as discussed below. Similarly, the eachrear stabilizer 204 may be have two rotor units mounted to it, both ofwhich are adapted to be used during vertical take-off and landing, andtransition, modes, but one of which is adapted to be fully stowed as lowdrag nacelle during forward flight.

A multi-modal wing mounted rotor unit 207 is adapted to use a first setof blades 212 for forward flight, and a second set of blades 213 forVTOL and transitional flight modes. The forward flight blades 212 may becoaxial to the VTOL blades 213, and may be attached at different ends ofthe same nacelle. In the case wherein the VTOL blades are articulated toa vertical position for VTOL flight modes, there may be two motorswithin the nacelle, one for each blade set. Similarly, a multi-modalrear mounted rotor unit 210 is adapted to use a first set of blades 211for forward flight, and a second set of blades 214 for VTOL andtransitional flight modes. The forward flight blades 211 may be coaxialto the VTOL blades 214, and may be attached at different ends of thesame nacelle. In the case wherein the VTOL blades are articulated to avertical position for VTOL flight modes, there may be two motors withinthe nacelle, one for each blade set.

In some aspects, all of the blades used to provide thrust for VTOL andtransitional modes are stowed during forward flight, and differentblades are used to provide thrust during forward flight. In someaspects, a single motor is used to provide power for different bladesets depending upon whether VTOL or forward flight modes are being used.In some aspects, two blade sets are placed in a coaxial configurationsuch that they are supported by a single nacelle, for example.

FIGS. 33-36 illustrate an aerial vehicle 200 in a forward flight modewherein all of the VTOL blades have been stowed, and nested in recesses,such that the nacelles present low drag. In a forward flight mode, thewing mounted rotor units 206, 207 are seen with all of the VTOL bladesstowed. Similarly, the rear mounted rotor units 205, 208 also have theirVTOL blades stowed. The forward flight blade set 211 of the multi-modalrear rotor assemblies 205 and the forward flight blade set 212 of themulti-modal wing rotor assemblies 207 are used to provide thrust duringforward flight.

FIGS. 39 and 40 illustrate a motor and rotor unit 260 adapted to use afirst set of blades 261 for a forward flight mode and a second set ofblades 263 for VTOL and transition modes, in a coaxial configurationthat shares a single motor for both blade sets. In this example, bothblades are powered by the same electric motor. The electric motor may beadapted with directional clutches such that when the motor is rotated ina first direction the forward flight blades 261 are engaged, and theVTOL blades 263 are idled. During forward flight the VTOL blades 264 maystow and may nest in recesses 264. During VTOL and transition modes themotor may rotate in a second direction such that the VTOL blades 264 areengaged, and the forward flight blades 261 are disengaged. In the VTOLmode the motor and rotor assembly may be articulated such that therotors and motor provide vertical thrust, with the entire motor andclutching unit, as well as both sets of blades, outboard of thepositioning mechanism, such that no mechanical power related to bladethrust need traverse the gimbaled joint.

FIGS. 41-44 illustrate a motor 265 with directional clutches 266, 267adapted to power a first set of blades when the motor is rotated in afirst direction, and to power a second set of blades when the motor isrotated in a second direction. In some aspects, the VTOL blade set andthe forward flight blade set may be oriented in different directionssuch that they both provide thrust in the same direction, although oneset is engaged when the motor rotates in a first direction, and thesecond set is engaged when the motor rotates in a second direction.

In a third embodiment of the present invention, as seen in a verticaltake-off configuration in FIGS. 45-48, an aerial vehicle 300 usesforward swept wings 302, 303 with rotors of different types adapted forboth vertical take-off and landing and for forward flight. The aircraftbody 301 supports a left wing 302 and a right wing 303. Motor drivenrotor assemblies 306, 307 on the wings include propellers which may stowand nest into the nacelle body. The aircraft body 301 extends rearwardand is also attached to raised rear stabilizers 304. The rearstabilizers have rear rotor assemblies 305, 308 attached thereto. Theaerial vehicle 300 is adapted for two passenger seats side by side, aswell as landing gear under the body 301.

The wing mounted rotor units 306, 307 are adapted to provide verticalthrust during take-off and landing modes. The inner rotor units 306 areadapted to deploy to a VTOL configuration using linkages as seen in FIG.38. The blades of the inner wing rotor units 306 are adapted to stowwhen in a forward flight configuration, with the blades nested intorecesses in the nacelle. The wing tip rotor units 307 are adapted torotate relative to the wing such that the nacelle maintains its shapewhether in a VTOL or a forward flight configuration. The VTOL blades 313are used for VTOL and transition modes, and the forward flight blades312 are used for forward flight, with the VTOL blades stowed and nested.The nacelle that maintains its shape allows for the use of a singlemotor to power either of the blade sets. The motor may use directionalclutches such that the motor direction determines which of the bladesets is powered.

Similarly, the blades of the inner tail rotor units 308 are adapted tostow when in a forward flight configuration, with the blades nested intorecesses in the nacelle. The rear tip rotor units 305 are adapted torotate relative to the wing such that the nacelle maintains its shapewhether in a VTOL or a forward flight configuration. The VTOL blades 314are used for VTOL and transition modes, and the forward flight blades311 are used for forward flight, with the VTOL blades stowed and nested.

In an exemplary configuration of the third embodiment, the aerialvehicle has 12 rotors and weighs 900 kg. The rotor diameter is 1.1meters, with a thrust per rotor of 736 N. The continuous rpm of themotor at sea level is 1850 rpm, with a maximum of 2270 rpm. The wingspanis 8.9 meters. The battery mass is 320 kg, and the mass per motor is 9kg. The cruise speed is 320 km/h. The continuous hover power per motoris 19 shaft kW.

FIGS. 49-52 illustrate a fourth embodiment of an aerial vehicle 400 in atake-off configuration. A box wing design is seen with the rotorassemblies deployed into vertical take-off configuration.

FIGS. 53-56 illustrate a fourth embodiment of an aerial vehicle 400 in aforward flight configuration. As seen the rotor assemblies are rotatedinto a forward flight configuration. Some of the blades of the rotorassemblies have been stowed to reduce drag in this forward flight mode.

In some aspects, aerial vehicles according to embodiments of the presentinvention take-off from the ground with vertical thrust from rotorassemblies that have deployed into a vertical configuration. As theaerial vehicle begins to gain altitude, the rotor assemblies may beginto be tilted forward in order to begin forward acceleration. As theaerial vehicle gains forward speed, airflow over the wings results inlift, such that the rotors become unnecessary for maintaining altitudeusing vertical thrust. Once the aerial vehicle has reached sufficientforward speed, some or all of the blades used for providing verticalthrust during take-off may be stowed along their nacelles. The nacellesupporting the rotor assemblies may have recesses such that the bladesmay nest into the recesses, greatly reducing the drag of the disengagedrotor assemblies.

As evident from the above description, a wide variety of embodiments maybe configured from the description given herein and additionaladvantages and modifications will readily occur to those skilled in theart. The invention in its broader aspects is, therefore, not limited tothe specific details and illustrative examples shown and described.Accordingly, departures from such details may be made without departingfrom the spirit or scope of the applicant's general invention.

What is claimed is:
 1. An aerial vehicle adapted for vertical take-offand horizontal flight, said aerial vehicle comprising: a main vehiclebody; a right side wing, said right side wing comprising a forward sweptwing, one or more right side wing rotor assemblies, said one or moreright side wing rotor assemblies comprising a propeller and a motor,wherein one or more right side wing rotor assemblies are attached tosaid right side wing along a middle section of the wing span, andwherein said one or more right side wing rotor assemblies protrudeforward of the leading edge of said right side wing, and wherein thecenters of mass of each of the one or more right side wing rotorassemblies are forward of the leading edge of said right side wing; anda left side wing, said left side wing assembly comprising a forwardswept wing; one or more left side wing rotor assemblies, said one ormore left side wing rotor assemblies comprising a propeller and a motor,wherein one or more left side wing rotor assemblies are attached to saidleft side wing along a middle section of the wing span, and wherein saidone or more left side wing rotor assemblies protrude forward of theleading edge of said left side wing, and wherein the centers of mass ofeach of the one or more left side wing rotor assemblies are forward ofthe leading edge of said left side wing.
 2. The aerial vehicle of claim1 wherein said one or more right side wing rotor assemblies are attachedto said right wing by a deployment mechanism adapted to deploy said oneor more right side wing rotor assemblies from a forward facinghorizontal flight configuration to a vertical take-off configuration,and wherein said one or more left side wing rotor assemblies areattached to said left wing by a deployment mechanism adapted to deploysaid one or more left wing rotor assemblies from a forward facinghorizontal flight configuration to a vertical take-off configuration. 3.The aerial vehicle of claim 2 wherein said motor of each one or moreright side wing rotor assemblies is an electric motor, and wherein saidmotor of each one or more left side wing rotor assemblies is an electricmotor.
 4. The aerial vehicle of claim 2 wherein said one or more rightside wing rotor assemblies and said one or more left side wing rotorassemblies comprise propeller blades adapted to pivot from a deployedconfiguration to a stowed configuration.
 5. The aerial vehicle of claim4 wherein stowed propeller blades reside in recesses within a rotormounting nacelle.
 6. An aerial vehicle adapted for vertical take-off andhorizontal flight, said aerial vehicle comprising: a main vehicle body;a right side wing, said right side wing comprising a partially forwardswept wing, one or more right side wing rotor assemblies, said one ormore right side wing rotor assemblies comprising a propeller and amotor, wherein one or more right side wing rotor assemblies are attachedto said right side wing along a middle section of the wing span, andwherein said one or more right side wing rotor assemblies protrudeforward of the leading edge of said right side wing, and wherein thecenters of mass of each of the one or more right side rotor assembliesare forward of the leading edge of said right side wing; and a left sidewing, said left side wing assembly comprising a partially forward sweptwing; one or more left side wing rotor assemblies, said one or more leftside wing rotor assemblies comprising a propeller and a motor, whereinone or more left side wing rotor assemblies are attached to said leftside wing along a middle section of the wing span, and wherein said oneor more left side wing rotor assemblies protrude forward of the leadingedge of said left side wing, and wherein the centers of mass of each ofthe one or more left side wing rotor assemblies are forward of theleading edge of said left side wing.
 7. The aerial vehicle of claim 6wherein said one or more right side wing rotor assemblies are attachedto said right wing by a deployment mechanism adapted to deploy said oneor more right side wing rotor assemblies from a forward facinghorizontal flight configuration to a vertical take-off configuration,and wherein said one or more left side wing rotor assemblies areattached to said left wing by a deployment mechanism adapted to deploysaid one or more left wing rotor assemblies from a forward facinghorizontal flight configuration to a vertical take-off configuration. 8.The aerial vehicle of claim 7 wherein said one or more right side wingrotor assemblies comprise an electric motor, and wherein said one ormore left side wing rotor assemblies comprise an electric motor.
 9. Theaerial vehicle of claim 7 wherein said one or more right side wing rotorassemblies and said one or more left side wing rotor assemblies comprisepropeller blades, said propeller blades adapted to pivot from a deployedconfiguration to a stowed configuration.
 10. The aerial vehicle of claim9 wherein stowed propeller blades reside in recesses within a rotormounting nacelle.
 11. The aerial vehicle of claim 2 wherein the spinaxis of the propellers of the one or more right side rotor assembliesare forward of the leading edge of the right side wing when in thevertical take-off configuration, and wherein the spin axis of thepropellers of the one or more left side rotor assemblies is forward ofthe leading of the left side wing when in the vertical take-offconfiguration.
 12. The aerial vehicle of claim 7 wherein the spin axisof the propellers of the one or more right side rotor assemblies areforward of the leading edge of the right side wing when in the verticaltake-off configuration, and wherein the spin axis of the propellers ofthe one or more left side rotor assemblies is forward of the leading ofthe left side wing when in the vertical take-off configuration.